Peyton Manning has been hearing from the skeptics for years. Ever since he missed all of 2011 due to a neck injury, he's been on fan radars as a quarterback primed for an inevitable decline.

Time and time again, though, Manning has managed to defy those doubters. No single performance affirms his endurance more than the 2013 season-opener, when Manning lit up the Baltimore Ravens for an NFL record-tying seven passing touchdowns.

Coming off a playoff loss to the Ravens in January, Manning had fans eager to see he could rebound from another disappointing performance. Manning pleased Broncos fans -- and, even more, his fantasy football owners -- with a record-setting day that ranks among the best one-week fantasy performances for any NFL player.

Manning's 46 fantasy points came in a deluge of scoring that quickly buried the Ravens. After spotting Baltimore a seven-point lead, the Broncos swapped touchdowns twice with their opponent in the second quarter.

Then, in the second half, Manning threw four unanswered touchdown passes to break the game open and erase all doubts surrounding his longevity.

Manning also racked up 462 passing yards in a 49-27 win.

"He's phenomenal," teammate Julius Thomas said of Manning after the game. "To continue to come out every year and put that kind of performance on for us, it's amazing."

As Manning enters the 2015 season, he faces many of the same doubts that followed him in 2013. The quarterback may not play forever, but he's proven his critics wrong enough times that, even at 39, betting against him seems like a mistake.